:root {
  box-sizing: border-box;
}

*::before,
*::after {
  box-sizing: inherit;
}

html {
  height: 100%;
}

body {
  height: 100%;
  margin: 0;
  padding: 0;
}

.calculator {
  height: 100%;
  display: flex;
  flex-direction: column;

  &__display {
    background-color: #858694;
    flex: 0;
    min-height: 20vh;

    > div {
      // 将显示区，垂直居中，水平靠右
      display: flex;
      flex-direction: row-reverse;
      align-items: center;

      font-size: 2.8rem;
      color: white;
      padding: 0.35rem;
      height: 100%;
    }
  }

  &__button_panel {
    flex: 1;
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;

    button {
      border: 0;
      padding: 0;
      margin: 0;
    }

    .row {
      width: 100%;
      display: flex;

      margin-bottom: 1px;

      &:last-child {
        margin-bottom: 0;
      }
    }

    .button {
      width: 25%;
      background-color: #e0e0e0;
      // text-align: center;
      margin-right: 1px;
      font-size: 2rem;

      &:last-child {
        margin-right: 0;
      }

      &.button--wide {
        width: 50%;
      }

      &.button--orange {
        background-color: #f5923e;
      }
    }
  }
}
